Cartridge seal stack

ABSTRACT

A cartridge seal stack utilizes a plurality of rotary cartridge seals each including a cold flowable plastic ring having a body for sealably engaging a housing bore and a lip for sealably engaging a shaft rotating within the housing bore. A spring is provided and disposed between the body and the lip for biasing the lip against the shaft and a separable metal retainer is provided for fixing the plastic ring within the housing bore and around the shaft. The separable metal retainer includes a surface of revolution with a rear portion having a radius suitable for press fitting into the housing bore and a front portion of lesser radius ending the ring. An internal groove is provided in the body of the plastic ring for engaging the ring in order to latch the plastic ring and metal retainer together. A spring portion connecting the retainer rear portion and the ring is provided for controlling residual stress in a radial direction within the plastic ring and preventing shrinkage of the plastic ring toward the shaft.

The present application is a continuation-in-part of U.S. Ser. No.09/037,324 filed Mar. 9, 1998, now U.S. Pat. No. 6,050,572.

The present invention generally relates to a stack of cartridge rotaryseals that are pressed into a housing and provide a seal around a shaftat relatively low pressures under various fluid environments. Moreparticularly, the present invention is directed to a stack of cartridgeseals mounted in a housing or on a shaft, which are designed primarilyfor use in reciprocating, rotary and static applications.

Cartridge rotary seals have been used for many years in a variety ofapplications for the sealing of various types of fluids and gases.Generally these seals use an elastomer as the seal material and suchelastomer is molded and bonded to a supporting metal ring.

The materials described in this application utilize various types ofplastics, such as ploytetrafluoroethylene PTFE because it exhibitsrelatively low friction and it is chemically inert and can withstand avariety of temperatures, thus enabling their use under conditions withno lubrication. Other plastic materials may be used, such as ultra highmolecular weight polyethylene, but it has limited temperaturecapabilities and limited chemical compatibility with a high degree offriction.

The prior art cartridge seals utilized the elastomer in a bondedrelationship and continuous tube bears around the shaft.

As hereinabove noted, when plastics are utilized, like PTFE, the plasticis mechanically retained to the metallic ring and the entire assembly ispressed into the housing with a high degree of interference between theOD of the seal and the housing to permit retention of the seal assemblyinto the housing and at the same time, providing static sealing againstthe housing. Dynamic sealing between the seal and the shaft is providedby the contact between the plastic and the shaft.

A common problem with the prior art is that the elastomer when subjectedto heat, produced a high degree of friction and wear and also havelimited chemical compatibility that limits the life of the seal and cancause seal failure.

Heretofore seals have been stacked between a housing and the shaft inorder to enhance overall sealing therebetween. Generally, the type ofseals that have been used for stacking are known as "V-Rings". Suchrings are circular and have a "V" cross section. The rings are stackedwith a hard support ring that bears against a housing end. The V-Ringsstack is generally made from the elastomeric materials or combinationsof elastomeric materials as well as plastics, such as PTFE andcombinations thereof. Unfortunately, fluid pressure applied to the stackis transmitted equally throughout the entire seal stack so all sealswere subject to the fluid pressure. In addition, heretofore, sealsstacks utilizing V-Rings provide for no radial adjustment. Accordingly,as the seals wear, leakage increases and eventually the replacement ofthe seals is necessary due to such leakage.

The present invention provides for a seal stack assembly in whichpressure is concentrated on a primary seal while other seals in thestack provide other functions, such as better sealing, longer life ofvariations and design, etc. Accordingly, the seal stack in accordancewith the present invention can withstand fluid pressure with littledeformation.

SUMMARY OF THE INVENTION

The rotary cartridge seal stack assembly in accordance with the presentinvention generally includes a plurality of rotary cartridge sealsdisposed in an abutting relationship with one another, the plurality ofcartridge seals being disposed between a housing bore in a shaft.

In one embodiment, each of the cartridge seals include a cold flowableplastic ring having body means for sealably engaging a housing bore andlip means for sealably engaging a shaft rotating within the housingbore. Separable metal retainer rings are provided for fixing the plasticring between the housing bore and around the shaft with the separablemetal retainer means each having a surface of revolution with a rearportion having a radius suitable for press fitting into the housingbore.

An internal groove in the body means is provided for engaging the ringin order to latch the plastic ring in metal retainer means together withresidual stress in both axial and radial directions with the plasticring, due to the groove and ring dimensions as well as shape. Theinternal groove has a diameter greater than the ring, and a width of theinternal groove is smaller than a width of the ring in order to maintainaxial stress in the plastic ring.

In another embodiment, the present invention each of the rotary sealcartridges include a cold flowable plastic ring having body means forsealably engaging housing bore and lip means for sealably engaging ashaft rotating within the housing bore. Spring means are provided anddisposed between the body means and lip means for biasing the lip meansagainst the shaft.

A separable metal retainer provides means for fixing the plastic ringand spring within the housing bore and around the shaft with theseparable metal retainer having a surface of revolution having a radiussuitable for press fitting into the housing bore and a front portion oflesser radius ending in a ring. The rear portion of the metal retainerand the ring are connected by a thin spring portion.

The means defining an internal groove in the body means in provided forengaging the ring therein in order to latch the plastic ring and metalretainer means together with residual stress in a radial directionwithin the plastic ring due to biasing action by the retainer meansspring portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention would be betterunderstood by the following description when considered in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a cross sectional view of a stackable rotary cartridge seal,in accordance with the present invention, disposed between a housing anda shaft with the seal generally including a plastic ring with aseparable metal retainer for fixing the plastic ring within the housingand around the shaft;

FIG. 2 is an enlarged cross sectional view of a portion of the sealshown in FIG. 1 showing greater detail of the engagement between themetal retainer and the plastic ring;

FIG. 3 is a cross sectional view of another stackable seal in accordancewith the present invention in which a spring is disposed in a positionfor biasing a lip of the plastic ring against a shaft and a metalretainer includes a step for facilitating separation of the metalretainer from the housing bore;

FIG. 4 is another embodiment of the present invention similar to thatshown in FIG. 1, but with the plastic ring having a lip thereon with anenlarged head portion;

FIG. 5 is a cross sectional view of yet another embodiment of thepresent invention in which the plastic ring includes a thin forwardportion and radial stress, as hereinafter discussed in greater detail,is provided by an extended or cantilever portion of the metal ring;

FIG. 6 is an enlarged cross sectional view taken along the line 6--6 ofFIG. 5 showing a groove and dovetail arrangement for facilitating coldflow of plastic material;

FIG. 7 is a cross sectional view of another embodiment of the presentinvention illustrating the application of radial stress in the plasticring;

FIG. 8 is a cross sectional view of yet another embodiment of thepresent invention showing a ring portion in the metal retainer having agenerally arrow shaped cross section;

FIG. 9 is a view taken along the line 9--9 of FIG. 7 showinglongitudinal slots in the metal retainer;

FIG. 10 is a view taken along the line 10--10 of FIG. 8 showing flatportions on a forward portion of the plastic ring to prevent rotationthereof within the housing;

FIG. 11 is yet another embodiment of the present invention illustratingthe use of a spring disposed within the plastic ring for biasing the lipand bearing against the metal retainer;

FIG. 12 is another illustration of the embodiment shown in FIG. 11showing its ability to be disposed between the housing and the shaft ina reversed direction;

FIG. 13 is a cross sectional view of another embodiment of the presentinvention showing a rotary cartridge seal, disposed between the housingand the shaft, with the seal generally including a plastic ring withseparable metal retainer for fixing a plastic ring within the housing onthe shaft, the retainer including a spring portion for controllingresidual stress in a radial direction within the plastic ring andpreventing shrinkage of the plastic ring toward the shaft;

FIG. 14 is a cross sectional view of another embodiment of a stackableseal cartridge in accordance with the present invention utilizing aretainer having a depending thin wall lug for maintaining a springwithin the plastic ring and for facilitating removal of the seal frombetween the housing and the shaft;

FIG. 15 is another embodiment of the present invention showingvariations in wall thickness of the retainer;

FIG. 16A-16H show various configurations of the locking metal retainerthat affect the force applied to the plastic ring and variations of suchforce;

FIG. 17A-17C show variations of the embodiment shown in FIG. 13;

FIG. 18 shows a seal design in accordance with the present inventionutilized in a captivated seal gland configuration;

FIG. 19 shows the seal shown in FIG. 18 used as an uncaptivated sealgland;

FIG. 20 shows an embodiment of the present invention utilizing agarter-type spring loading a lip off the plastic ring;

FIG. 21 shows another embodiment of the present invention utilizing aplastic ring with a memory lip;

FIG. 22 shows another embodiment of the present invention in which theplastic ring is utilized to provide a clearance seal against a shaftprimarily for keeping dust and dirt out;

FIG. 23 is a variation of the embodiment shown in FIG. 22;

FIG. 24 is an embodiment including the features of FIGS. 21 and 22;

FIG. 25 is a variation of the design shown in FIG. 24 when two seals areassembled back to back;

FIG. 26 shows yet another embodiment of the present invention in whichthe metal retainer ring is pressed into the housing holding a plasticring seal utilizing two memory lips;

FIG. 27 is a variation of the embodiment shown in FIG. 13 in which aninside diameter of the retainer has been made slightly larger than theshaft diameter;

FIG. 28 is another embodiment of the present invention in which theretainer ring provides a labyrinth seal at the ID thereof, the retainerbeing made of a bearing metal material or a high modulus plastic toprovide sufficient force to retain the seal and housing and not damagethe shaft;

FIG. 29 is another embodiment of the present invention utilizing aV-type, or finger-type metallic spring;

FIG. 30 is yet another embodiment of the present invention utilizing aback-up ring;

FIG. 31 shows another embodiment of the present invention utilizing twoseals of the same design placed end to end;

FIG. 32 is an embodiment similar to FIG. 31 in which the relativeplacement of the seals is reversed;

FIG. 33 shows another embodiment of the present invention in which agarter-type is used to apply an extension spring force on the seal ontothe shaft for high speed applications along with a secondary memory typeseal to prevent contaminants from coming the direction opposite thepressure applied;

FIG. 34 is yet another embodiment of the present invention in which theseal is mounted on the shaft instead of the housing;

FIG. 35 is an illustration of a prior art cartridge seal stack utilizinga typical V-Ring seal;

FIG. 36 is an illustration of a cartridge seal stack in accordance withthe present invention which allows individual sealing of each sealcartridge. This permits the first seal to provide the primary sealingfollowed by the second seal and the third seal;

FIG. 37 shows a seal stack mounted on a housing, only two sealcartridges being shown for illustration;

FIG. 38 shows a seal stack assembly similar to that shown on FIG. 37with individual seal cartridges mounted on the shaft instead of thehousing;

FIG. 39 shows an alternative embodiment of the seal stack in accordancewith the present invention in which a support plate locking ring servesan added function by maintaining a close tolerance with the shaft;

FIG. 40 shows a seal stack assembly mounted in a cartridge bearingassembly;

FIG. 41 shows another variation of the seal stack assembly in accordancewith the present invention wherein individual seal cartridges havedifferent lip widths;

FIG. 42 shows yet another alternate design in accordance with thepresent invention in which a primary seal cartridge is larger in crosssection and seal width than a secondary seal cartridge;

FIG. 43 shows another seal stack assembly in accordance with the presentinvention in which a primary seal cartridge is wider than the secondaryseal cartridge with both having the same gland housing diameter;

FIG. 44 illustrates a seal stack assembly in accordance with the presentinvention utilizing different types of seal energizers, or springs,within the individual cartridge seals; and

FIG. 45 is another embodiment of the present invention in which theindividual seal cartridges of the stack utilize a circular canted coilspring or "O" Ring.

DETAILED DESCRIPTION

A description of individual seal cartridges suitable for stacking inaccordance with the present invention will at first be discussed.Thereafter, the stacking of such individual seal cartridges will bedescribed.

Turning now to FIG. 1, there is shown a rotary cartridge seal 10 inaccordance with the present invention which generally includes a coldflowable plastic ring 12 having a body 14, which provides means forsealably engaging a housing bore 16, formed in a housing 18, and a lip20 which provides means for sealably engaging a shaft 26. In FIG. 1 thelip 20 is shown in dashed line 20a in a position before seal 10 isinserted between the housing 18 and shaft 26 and the dashed line 20brepresents an effective range of sealing for the lip 20.

Importantly, the present invention utilizes a cold flowable plasticmaterial, such as PTFE, PTFE compositions with various fillers or UHMWto enable the flow of the material when properly stressed in accordancewith the present invention. In fact, the residual stress maintains theplastic ring in intimate contact with a separate metal retainer 30 in amanner which creates residual stress for maintaining the componentstogether within specific temperature parameters.

No permanent bonding occurs between the plastic ring 12 and the metalretainer 30, with the latter providing a means for retaining the plasticring within the housing bore 16 and around the shaft 26. As shown, theseparable metal retainer 30 includes a surface of revolution 34 having arear portion 36 with a diameter suitable for press fitting into thehousing bore 16 and a front portion 38 having a lesser diameter whichends in a ring 40.

An internal groove 44 within the plastic ring body 14, as more clearlyshown in FIG. 2, has a radius r₁ greater than a ring radius r₂,resulting in a clearance C₁. Such clearance facilitates assembly of themetal part into the plastic groove. The metal ring front portion 38adjacent the ring 40 has an outside radius less than a contacted insideradius of the plastic ring body 14 indicated as interference I₁, inorder to maintain the radial stress in the plastic ring body 14.

In addition, a width of the groove 44 is greater than a width of thering as indicated by the clearance C₂. Such clearance facilitatesassembly of the two parts. However, upon insertion of the seal 10,between the housing 18 and the seal O.D. 12, causes cold flow of thePTFE into the groove 44 and around the ring 40 creating an axial stressin the plastic ring 12. This deformation force can be applied radially,axially or a combination of radial axial forces with the purpose ofproviding locking action between the plastic ring 12 and the metalretainer 30.

Depending upon the wall thickness of the plastic ring 12, additionalradial loading may be provided by the metal retainer 30 so as to exertadded axial spring-like force to maintain greater and longer intimatecontact between the plastic ring 12 and the housing 18. As hereinafterdescribed in greater detail with regard to other embodiments of thepresent invention, seals in accordance with the present inventionprovide sealing throughout a greater temperature range. The metallicretainer 30 may be designed to add flexibility and increase the loadingforce as the temperature increases and the bearing stress of the PTFEdecreases. In this manner, a spring force provided by the metallicretainer 30 maintains an improved sealing ability of the cartridge seal10 while maintaining contact between the seal OD and the housing 18.

The groove 44 in the plastic ring body 14 and the ring 40 portion of themetal retainer 30 is assembled as a rotary cartridge seal 10 by forcingthe metal retainer 30 into the plastic ring 12 which expands the plasticring 12 radially and causes the plastic ring 12 to "snap" which createsa diametrical interference between the ID of the plastic ring 12 and theOD of the metal retainer 30 at an area A so that a residual circularstress remains.

In this instance, "snap" refers to the radial and/or axial expansion ofthe plastic which allows plastic to return to its normal position butcreates a radial or axial residual stress around the expanded surfaces.

Upon assembly of the plastic ring 12 and metal retainer 30 into thehousing bore 16 and over the shaft 26 causes a diametrical force, ashereinabove noted, to be applied on the plastic ring 12. Interferencebetween the OD of the plastic ring 12 and the housing bore 16 provides aradial load on the plastic ring 12 for maintaining intimate contactbetween the OD of an area A of the metal retainer 30 and the plasticring 12.

Inasmuch as this interference adds to stress, which is maintainedbetween the two surfaces, the metal retainer 30 and plastic ring 12 arelocked both axially and radially. Excess plastic flows around theoutside radius r₃ of the plastic seal which creates an interference withthe housing indicated at B in FIG. 2. In addition, this cold flow,enabled through the use of PTFE, causes filling of the clearance C₂ andgap between the ring 40 and the groove 44 to provide axial stress andpositive latching or locking of the metal retainer 30 and the plasticring 12. Naturally, in this regard, proper spring-like metal retainer 30material must be utilized, such as, for example, preferably stainlesssteel.

It should be appreciated that the plastic ring 12 and the metal retainer30 may be locked in place by either an axial locking action, a radiallocking action or a combination of both. That is, there may be axialclearance at assembly, which may or may not be filled by the coldflowing of the material, as in C₂, FIG. 2, or radial clearance atassembly as in C₁ and such clearance may remain or may not remain aftercold flow of the material. But in all cases, there will be some sort ofresidual induced stress, be axial, radial, or a combination of axial andradial.

More specifically, and by way of example only, the plastic PTFE ring mayhave an outside radius of between about 19.000 mm and about 19.126 mmwith a housing having a radius between about 19.063 mm and about 19.037vacating a radial interference ranging between about 0.089 mm-0.0035" toabout 0.063 mm-0.0024".

The plastic ring groove may have a radius of r₁, between about 17.907 mmand about 17.882 mm with a metal ring groove diameter r₂ of betweenabout 17.832 mm and about 17.356 mm having a radial clearance betweenabout 0.000 mm to about 0.051 mm.

The plastic ring groove radius r₅ may have a radius of between about17.526 mm and about 17.500 mm with a metal ring radius r₄ of betweenabout 17.597 mm and about 17.551 mm having a radial interference betweenabout 0.092 mm to about 0.025 mm.

In addition, the difference between the groove 44 width and ring 40width may provide for clearance C₂ of between about 0.000 mm and about0.051 mm.

This configuration enables sealing between the housing 18 and the shaft26 at temperatures between about -20° C. and about 100° C. at shaftrotational speeds of up to 5000 RPM, when using PTFE compositions, asfor example, containing 20% carbon, 5% graphite, 78% PTFE.

Another embodiment 60 in accordance with the present invention is shownin FIG. 3 in which plastic ring 62 includes a second groove 64 adjacenta lip 66 is provided for receiving a spring 68 for biasing the lip 66against the shaft 26.

In addition, a metal retainer 70 which is similar in design to theretainer 30 but which includes an inwardly extending step 72 whichprovides means for facilitating separation of the metal retainer 70 fromthe housing bore 16 along with the plastic ring 62.

A further embodiment 78 of the present invention is shown in FIG. 4 inwhich common character references refer to identical or substantiallythe same elements shown in FIG. 1. In this embodiment 78, a plastic ring80 includes a lip portion 82 having a head 84 thereof which provides ameans for contacting the shaft 26 over a greater area.

Turning now to FIG. 5, yet another embodiment 90 in accordance with thepresent invention includes a plastic ring 92 and a metal retainer 94. Inthis instance, the plastic ring 92 includes a relatively thin wallthickness t₁, and accordingly, no radial snapping action occurs due tothe flexibility of the plastic ring 92 at that point. However, snappingaction occurs axially as hereinabove described in accordance with theembodiments shown in FIGS. 1-4.

In the rotary cartridge seal embodiment 90 shown in FIG. 5, the ID ofthe plastic ring 92 expands radially during assembly which allowspartial entry of the metal retainer 94 into the plastic ring groove 96.Sufficient force is applied axially which causes axial deformation ofthe plastic ring 92 at the groove 96, that creates an axial snap actionby compressing and deforming the plastic ring 92 axially around thegroove 96 area.

The axial deformation of the plastic ring 92 causes a residual stressthat maintains axial as well as radial contact with the groove 96 inorder to lock the plastic ring 92 in the metal retainer 94 together.This configuration adds to reliability and ability of the seal 90 athigher temperatures through the combined axial and radial residualstresses that remain in the plastic ring 92.

The groove ring 100 on the metallic retainer 94 may be dovetailed asshown in FIG. 6, or it may be squared. A dovetailed design facilitatesassembly of the metal ring 94 into the plastic ring 92. In addition thedovetail 102 as well as a corresponding dovetail 104 in the plastic ring92 enables a greater amount of cold flowing of the PTFE material of thering 92 into the area therebetween. This provides for a more substantiallocking of the plastic ring 92 and the metal retainer 94.

Referring to FIG. 7, another rotary cartridge seal embodiment 110 inaccordance with the present invention which is similar in design to theseal 10 hereinabove discussed in connection with FIG. 1.

A plastic ring 112 is provided as well as a metallic retainer 114.However, in this instance, a metal retainer 114 is thin-walled. Themetal retainer 114 includes a long cantilever front portion 120 whichmagnifies radial deflection thereof as indicated by the dashed line 122in FIG. 7. This added spring deflection increases the radial load on thebody portion 122 of the plastic ring 112 which provides additional forcein addition to the residual force that already exists so that the sealassembly 110 can be used at higher temperature.

The circular deflection of the metal retainer 114, is sufficient tomaintain intimate contact between the OD of the plastic ring 112 and themetal retainer 114. It should be appreciated that the residual stressthat occurs radially and axially during assembly decreases as thetemperature increases. Accordingly, this added radial spring force,caused by the thin section cantilever 122, takes up such loss ofresidual stress at elevated temperatures and permits the seal assemblyto operate at higher temperatures due to such added radial deflection.The seal assembly 110 is pressed and retained into a housing 126 byinterference that occurs between the metal ring OD and the housing 16.

FIG. 8 shows a further rotary cartridge seal embodiment 130 inaccordance with the present invention including a plastic ring 132 andmetal retainer 134 for insertion into a housing 136. A thin cantileversection 140 of the metallic retainer 132 is provided with anarrowhead-shaped head 142, which is forced into intimate contact with acorrespondingly shaped groove 144 to create axial locking between theplastic ring 132 and the metal retainer 134. The arrowhead 142 may havea dovetail design as shown in FIG. 6 to improve locking action. Radialinterference is provided between the seal OD and the housing 136 toimprove seal performance.

Improved flexibility of the cantilever portion 120 of the metallicretainer 114 shown in FIG. 7 may be obtained by providing longitudinalslots 150 as shown in FIG. 9. Slots 150 provide for added deflection andhence greater flexibility of the metal retainer 114 in order toaccommodate larger temperature ranges as may be desired.

Further, as shown in FIG. 10, the plastic ring 132 may include aplurality of flats 154 on a circumference 156 in order to preventrotation of the plastic ring 132 during operation. As hereinabove noted,the cold flow characteristics of the PTFE material utilized in the ring132 enable material to flow into the flats thereby preventing rotationof the plastic 132.

Yet another embodiment 160 of the present invention is shown in FIGS. 11and 12. The rotary cartridge seal 160 design enables the cartridge seal160 to be inserted and utilized between a housing 162 and shaft 164 inopposite directions as are correspondingly represented in FIGS. 11 and12. A metal retainer 166 is similar to the retainer hereinabovedescribed in connection with retainer 30 shown in FIG. 1, and theplastic ring 170 having a lip 172 is similar in design and function tothe plastic ring 62 and lip 66 as described in connection with FIG. 3.In this instance, a plastic ring 170 is U-shaped and a spring 180 isdisposed therein between a lip 172 and the metal retainer 166 with thespring 180 being disposed in the position bearing against a metallicretainer front portion 182. This configuration provides for increasedsealing ability.

It should be noted that sealing lip designs indicated in FIGS. 1 and 4may be used in place of the designs indicated in FIGS. 11 and 12.

It should be appreciated that the hereinabove discussed rotary cartridgeseals, 10, 60, 78, 90, 110, 130 and 160 provide for an assembly thatcreates residual stresses to maintain intimate contact between theplastic rings and metal retainers within a specific temperature ranges,for example, between about -20° and about 100° C. Intimate contactbetween seal surfaces take up for variations that may occur to the PTFEmaterial during usage especially at elevated temperatures. Specificallydescribed dimensions and configurations with regard to clearanceshereinabove discussed, control the cold flow of the PTFE material, andlimit the shrinkage thereof, while maintaining residual stress in orderto maintain intimate contact between the plastic rings and correspondingmetallic retainers.

The hereinafter discussed embodiments in accordance with the presentinvention include means for reducing the assembly force required toassemble the seal and the housing, minimize the variation from seal toseal when assembling the seal into the housing and utilizing a springfor providing bias between a plastic ring seal and a shaft.

With reference to FIG. 13, there is shown a rotary cartridge seal 200 inaccordance with the present invention which generally includes a coldflowable plastic ring 202 having a body 204 which provides a means forsealably engaging a housing 206 bore 208 and a lip 210 which provides ameans for sealably engaging a shaft 212. A spring 220, disposed betweenthe body 204 and the lip 210, provides a means for biasing the lip 210against the shaft 212.

Separable metal retainer means 222 is provided for fixing the plasticring 202 within the housing bore 208 and around the shaft 212. Theretainer 222 includes a surface of revolution with a rear portion 224having a radius suitable for press fitting into the housing bore 208 anda front portion 226 of lesser radius ending in a ring 228. Thus, thelocking ring-retainer 222, in addition to retaining the seal assembly200 in the housing 206, also retains the spring energizer 220 within theconfines of the seal assembly 200. Between the rear portion 224 and thering 228 is a spring portion 232 which provides a means for controllingthe residual stress in a radial direction within the plastic ring 202and prevent shrinkage of the plastic ring 202, particularly the bodyportion 204 toward the shaft 212.

As shown in FIG. 13, clearances 236 and 238 are provided between thering 228 and the body portion 204 to facilitate assembly of the seal200. A thin area indicated at 240 of the spring portion 232 of theretainer 222 is utilized to control the spring force of the retainer 222against the body portion 204. Accordingly, pressure is applied to thebody portion 204 at a surface 244.

In addition, because the retainer 222 is flexible through the springportion 232, the force necessary to assemble the seal 220 between thehousing 206 and shaft 212 is significantly reduced. By varying theradial wall thickness of the plastic ring 202 and thickness of thespring portion 232, the seal can be tailored for use in a wideenvironment of pressures and temperatures.

The embodiment 200 further differs from the hereinabove discussedembodiment 10 in that a step 250 inwardly depending from the rearportion 224 of the retainer 222 facilitates removal of the seal 200 fromengagement with the housing 206 and shaft 212. A thickness indicated at252 of the step 250 provides support for the spring portion 232 andaccordingly provides a means for controlling the force needed to pressfit the retainer 222 into the housing bore 208.

With reference to FIG. 14, there is shown yet another embodiment 260 inaccordance with the present invention, common character referencesindicating identical or substantially the same structural components asshown in FIG. 13. In this embodiment the retainer 262 includes a widenedring portion 264 as referenced by the arrows 266.

In addition a rear portion 268 of the retainer 262 includes a thinflange 270 for engaging the housing bore 208 and an inwardly dependingflange 272 which provides a means for both holding the spring 220between the body 204 and lip 210 of the plastic ring 202 and forfacilitating removal of the seal 260 from engagement with the housingbore 208 and shaft 212.

The thin flange 270 reduces assembly force and can be of variousthicknesses to vary the assembly force. This embodiment reduces the massaround the metal loading portion 268 of the retainer 262 in order toincrease flexibility. This is especially important in small diameters.

A further embodiment 280 of the present invention is shown in FIG. 15 inwhich the retainer 282 includes a relatively thick body 284 and theplastic ring 286 includes an inwardly extending lip 288 which maintainsthe spring 220 within the seal 280. This embodiment is particularlyuseful for large diameter shafts.

FIGS. 16A-16H shows various metal retainer rings 290, 292, 294, 296,298, 300, 302, 304 which provide various forces and sealingcapabilities. As earlier indicated and with reference to FIG. 16A and16B, a wall thicknesses 310, 312 controls the force required to assemblethe seal. Various seals can be provided also to reduce the forcerequired to assemble the seal 290 into a bore, not shown in FIG.16A-16G. Particularly, the plurality of load rings 314 reduce surfacecontact as opposed to a flat surface 316 shown in FIG. 16E. It should beappreciated, however, that the flat areas as indicated by the arrows 318do provide seal stability after assembly.

As shown in FIG. 16C, the retainer 294 may be undercut 320 in order toreduce the mass of the retainer 294 while also reducing the forcerequired for assembly. The undercut 320 may be radial, or, as shown inFIG. 16G, the undercut 322, may be axial.

In FIG. 16H the retainer 304 has been modified to provide a circularundercut 306, similar to the retainer 302 shown in FIG. 16G, in order tocreate greater retainer flexibility for facilitating assembly of theretainer 304 with a plastic ring, not shown, into a housing, also notshown in FIG. 16H.

Variations and combinations of plastic ring body thickness and springportion thickness of the retainer are shown in FIGS. 17A, 17B, 17C. Eachof these seals 340, 342, 343, 344 show various thicknesses of theplastic body as indicated by the arrows 346, 348, 350 and spring portionas indicated by the arrows 354, 356. In FIG. 17A, the thick outside wall346, in combination with a thin spring portion 352, causes highshrinkage of the plastic when subjected to elevated temperatures. FIG.17B shows a comprising wall thickness of the spring portion 354 andplastic band 348, whereby a certain degree of shrinkage will occur onthe plastic rings. However, no defamation will occur on the springportion 354 due to greater thickness. FIG. 17C shows the embodiment 344with a thin plastic body 350 and a thickened spring portion 356. Thesevariations are shown in order to provide an understanding of the controlof radial stress in the plastic portions 346, 348, 350 through the useof a spring portion in the retainer.

FIG. 18 illustrates a seal 360 utilized as a captivated sealed gland.This type of design can be used in relatively high pressures because,upon application, the pressure, the housing 362 absorbs the pressureforce. The assembly force in this type of design should be just enoughto prevent the seal 360 from rotating which is caused by a frictiondeveloped between the seal 360 and the shaft 364. A minimum amount offorce is required which is desirable since damage to the seal isminimized during assembly. The force required to assemble the seal 360into the housing 362 will depend upon the seal diameter and seal crosssection and the reverse pressure acting on the back portion of the seal.

FIG. 19 shows a seal 370 utilized as an uncaptivated seal gland. In thisinstance, the force required to assemble the seal 370 will dependprimarily on the fluid pressure, acting on the seal plus safety factor.The larger the cross section of the seal, the greater the force thatwill be acting on the seal due to the fluid pressure trying todisassemble such seals from the housing 372. In this instance, theassembly force should be directly related to the force derived by thepressure acting on the seal 372. In the uncaptivated groove 374, thevariation assembly force should be minimum so as to minimize damage tothe seal 372 during assembly as the assembly force is applied directlyonto the plastic ring 376 and if excessive force is applied, it maycause damage to the ring 376. In this instance, it is desirable toincrease the area of contact between the plastic ring 376 and the metalring 380 of the retainer 382, such as illustrated in FIG. 14.

FIG. 20 shows an alternative embodiment 390 of the present invention inwhich a garter type spring 392 is utilized for biasing a lip 394 againsta shaft 396.

FIG. 21 shows yet another embodiment 400 in accordance with the presentinvention which utilizes a lip 402 as hereinabove discussed inconnection with FIG. 1.

FIG. 22 illustrates a seal 402 utilizing the principles of the springportion 404 of a retainer 406 as a clearance seal design primarily forkeeping dust and dirt from entering between the housing 408 and shaft410. In this instance, grooves 412 in an end 14 of the plastic ring 416are utilized to provide minimum friction between the seal 402 and theshaft 410.

FIG. 23 shows a variation 20 of a clearance seal similar to that shownin FIG. 22.

FIG. 24 shows a combination seal 422 utilizing both a clearance seal 424and a lip seal 426.

FIG. 25 shows yet another embodiment of the present invention whereintwo seals 432, 434 are utilized back to back.

FIG. 26 is yet another embodiment of the present invention in which twolips 440, 442 are used.

FIG. 27 shows an embodiment 450 of the present invention similar to thatshown in FIG. 13 but with a larger metal retainer step portion 452.

FIG. 28 shows another embodiment 460 of the present invention in whichthe metal retainer 462 includes a step portion 464 having grooves 466for providing a labyrinth seal with a shaft 468. In this instance, it ispreferable that the retainer 462 is formed out of a bearing metalmaterial, or a high modulus plastic that would provide sufficient forceto retain the seal and the housing 470 and not damage the shaft 468.

FIG. 29 shows another embodiment 480 of the present invention utilizinga V-type spring 482.

FIG. 30 shows yet another embodiment 486 of the present inventionutilizing a back-up ring 488.

FIG. 31 illustrates two seals 490, 492 disposed in abutting relationshipin a cavity 496 as will be hereinafter discussed in greater detail foruse in relatively low pressures.

FIG. 32 shows a variation of the design shown in FIG. 31 in which theseals 498, 500 are disposed back to back in an abutting relationship aswill be discussed hereinafter in greater detail.

FIG. 33 shows another seal 502 using various combinations of thefeatures hereinabove discussed.

FIG. 34 shows yet another embodiment of the present invention 504 inwhich the seal 504 is mounted in the shaft 506.

The present invention relates primarily to the manner in which thehereinabove individual seal cartridges may be stacked--one behind theother--to prevent the secondary in subsequent seals from collapsing whenunder high fluid pressure as will be hereinafter discussed in greaterdetail.

The present invention must be contrasted from a typical prior art sealstack 510 as shown in FIG. 35. This stack 510 utilizes individual V-ringseals 512 formed from elastomer or plastics. The individual seals 512are pressed fitted into a butting relationship by end pieces 514, 516which hold the stack 510 between a housing 520 and a shaft 522. Asapparent in FIG. 35 pressure, as indicated by the arrow 524, is appliedto the end piece 514 which is transmitted through all of the individualseals 512 to the end piece 516 and backing plate 526.

Accordingly, pressure is transmitted equally throughout the entire sealstack 510, thus, all the seal wear proportionately since the pressure isevenly applied throughout the entire seal stack. That is, each of theindividual seal 512 is under the same pressure. No radial adjustment isprovided, and accordingly, as the individual seal 512 wear leakageoccurs and eventually replacement of the entire stack is necessary.

This should be contracted with the rotary cartridge of seal stackassembly 530 in accordance with the present invention as shown in FIG.36 which illustrates a plurality of rotary cartridge seals 532, 534, 536disposed in an abutting relationship between a housing 540 and a shaft542.

It should be appreciated that the individual cartridge seals 532, 534,536 correspond to the embodiment 206 shown in FIG. 3. However, any ofthe hereinabove discussed individual seal cartridges may be utilized inaccordance with the present invention. Further, any of the embodimentshereinabove shown in FIGS. 1-34 may be used in any combination toprovide various seal stack configurations. The embodiment 532, 534, 536are only shown here as representative. Hereinafter other typicalcombinations of individual seal cartridges will be discussed in theformation of the seal stack in accordance with the present invention.

Briefly, each of the cartridge seals 532, 534 include the cold flowableplastic ring 544, 546, 548 respectively, along with springs 550, 552,554 and separable metal retainers 560, 562, 564 similar to thoseelements hereinabove discussed in connection with the embodiment 206shown in FIG. 13.

It should be easily appreciated that pressure represented by the arrow570 is applied to the first seal 532 since the seal 532 providesindividual sealing between the housing 540 and the shaft 542 of thefluid pressure. No significant fluid or fluid pressure is passed to thesubsequent seals 534, 536. Only a mechanical force generated against thefirst seal 532 by the fluid pressure is transferred to the abuttingseals 534, 536. A backing plate 572 stabilized the stack 530 between thehousing shaft 540 and shaft 542.

With reference to FIG. 37, there is shown a seal stack 580 disposedbetween a housing 582 and a reciprocating shaft 584. Seal ring 590, 592are identical as well as the springs 594, 596. The retainer rings 600,602 have a difference of length depending portions 604, 606. Ashereinabove described, the rings 604, 606 stabilized the assemblies bycreating an interference between an outside diameter 610, 612 and thehousing 582.

Springs 594, 596 provide a radial load onto the sealing ring 590, 592respectively to provide initial sealing. As the pressure acting on theseal increases the function of the spring 594, 596 decreases. Aclearance 620 exists between the shaft 584 and the depending portion 604to allow fluid to energize the sealing ring 590. The force due topressure applied on to the seal assembly 610 is to the seal assembly assimply 612 through the seal ring 590 and on to the retainer 606 of theassembly 612. A backup plate 624 supports the force developed by thepressure acting on both the seal assemblies 610, 612.

In this arrangement the seal assembly 610 is the primary seal and theseal assembly 612 is the secondary seal. The seal assembly 610 providesthe maximum sealing ability, in turn, results in the highest wear andthe seal assembly 612 acts as insurance, providing added reliability tothe seal assembly 610. Should the seal assembly 610 fail, seal assembly612 takes over as the primary seal. By stacking several seals ofpressure acting on the first seal 610 will always be greater than thesubsequent seals, and in such cases wear on the subsequent seal 612 willbe diminished depending upon the pressure acting on the subsequent seal612. Thus, the stacking of the seals maximizes the life of the stack580.

With reference to FIG. 38 there is shown another embodiment 650 inaccordance with the present invention in which individual sealassemblies 652, 654 are mounted on a shaft 656 for seal against ahousing 658.

FIG. 39 shows another embodiment 660 utilizing retainer rings 662, 664,666 having long depending portions 668, 670, 672 in order to provide aclose tolerance indicated at 674, 676, 678 between a shaft 680 and therings 662, 664, 666 respectively.

By maintaining this minimum clearance possible pressure differential maybe established between the initial pressure acting in the internalportion of the seal ring assembly 660. By maintaining a minimumclearance which is shown in FIG. 39, such pressure drop may be achieved,especially in those applications where variable pressure occurs duringthe operation of the unit such as those cases where the pressure appliedvaries with the cycling operation such as compressors, reciprocatingplunger pumps and so forth. In such cases the clearance seal allows apressure differential between the actual pressure applied in the actualpressure acting on the sealing lips 680, 682, 684 and lower the pressureacting on the sealing lips 680, 682, 684 the lower the seal wear.

Again, as hereinbefore discussed, by providing the seal stack 660,pressure on subsequent seals is diminished and therefore the forceacting on the sealing lips 682, 684 is also less.

The rings 668, 670, 672 are preferably made from metallic materials toprovide better support under conditions of high pressure, but elasticmaterials may be utilized to permit a closer minimum clearance gapbetween the shaft 680 and the depending portions of 668, 670, 678.Groove 690 also may by utilized to vary the degree of pressure dropacting through the clearance area.

Hereinabove seals stack assemblies 530, 580 are press fit between theshafts 542, 584 and respective housings 540, 582. In the embodiment 660shown in FIG. 39 canted coil spring assemblies 700, 702, 704 may beutilized to seal the stacks between the shafts 680 and housing 706.

With reference to FIG. 40 there is shown stacked seals 710, 712 in abearing assembly 714. In this instance should leakage occur past theseals 710, 712 such leakage may be removed through a central port 716.

With reference to FIG. 41 there is shown a seal stack assembly 720including two seals assemblies 722, 724 having sealing rings 726, 728with lips 730, 732 of different width. The primary seal 724 has ashorter width sealing lip 732 the secondary seal 722. Both seals 720,724 have the same outside diameter for mounting between a shaft 740 andthe housing 742. The shorter width sealing lip 732 offers an advantagein that the area in which the pressure applied thereto is less.Therefore the force acting on the sealing lip 732 is reduced by suchwidth differential and therefore, the possibility of seal weardecreases. However, the main disadvantage is that deflection of thespring 744 decreases, which, in some cases, may not be sufficient totake up the possible variations and eccentricities and misalignment thatmay occur on the shaft.

FIG. 42 illustrates another seal stack 750 in which the primary seal 752is larger in cross section than the secondary seal 754. In thisinstance, the housing 756 has two-step gland diameters 758, 760.

FIG. 43 shows an alternative rotary cartridge seal stack 764 in whichthe primary seal 766 is wider than the secondary seal 768 with both seal776, 768 having the same housing diameter 770.

FIG. 44 illustrates a seal stack 774 in accordance with the presentinvention in which the primary seal 776 and secondary seal 778 utilizedifferent types of springs. As shown, the seal 776 utilizes a ribbontype spring 780 and the secondary seal 778 utilizes a cantilever fingertype spring 782. Other types of springs 780, 782, or seal energizers,may be used instead of those illustrated. For example, elastomer "O"Rings, or elastomer filled springs may be utilized in the seals and theseal stacks of the present invention.

FIG. 45 shows yet another seal stack embodiment 800 in accordance withthe present invention in which the individual seal assemblies 802, 804are held within housing 806 through the use of circular canted coillocking springs, or "O" Rings 810 or 812 or a combination thereof.Alternatively, one of the assemblies 802, 804 may be press fit into thehousing 806 as hereinabove shown, and another seal assembly utilizingthe coil spring, 810, 812 may be abutted thereagainst.

Such springs were "O" Rings 812 may be utilized in certain circumstanceswhere an interference, or press fit may cause galling, or excessiveforce may be necessary, or there are wide variation in a housing bore820.

Although there has been hereinabove described a specific embodiment of arotary cartridge seal stack in accordance with the present invention,for the purpose of illustrating the manner in which the invention may beused to advantage, it should be appreciated that the invention is notlimited thereto. Accordingly, any and all modifications, variations, orequivalent arrangements which may occur to those skilled in the artshould be considered to be within the scope of the present invention asdefined in the appended claims.

What is claimed is:
 1. A rotary cartridge seal stack assemblycomprising:a plurality of rotary cartridge seals disposal in an abuttingrelationship between a housing bore and a shaft, each rotary cartridgereal comprising: a cold flowable plastic ring having body means forsealably engaging a housing bore and lip means for sealably engaging ashaft rotating within said housing bore; separable metal retainer meansfor fixing said plastic ring and spring within said housing bore andaround said shaft, said separable metal retainer means having a surfaceof revolution with a rear portion having a radius suitable for pressfitting into said housing bore; and means defining an internal groove insaid body means for engaging the ring therein in order to latch theplastic ring and metal retainer means together with residual stress inboth axial and radial directions within the plastic ring due to thegroove and ring dimensions and shape; said internal groove having adiameter greater than the ring and wherein a width of said internalgroove is smaller than a width of the ring in order to maintain axialstress in the plastic ring.
 2. The seal according to claim 1 whereinsaid internal groove has a radius greater than the ring and the metalretainer front portion adjacent the ring has an outside radius less thata contacted inside radius of the plastic ring body means adjacent saidinternal groove in order to maintain the radial stress in said plasticring.
 3. The seal according to claim 2 wherein a width of said internalgroove is greater than a width of the ring but less than a widthnecessary to accept excess plastic forced by the radial stress due tocold flow into said groove means thereby maintaining the axial stress inthe plastic ring.
 4. The seal according to claim 3 wherein said lipmeans includes head means, disposed at an end of said lip means, forengaging the shaft.
 5. The seal according to claim 4 wherein saidplastic ring further comprises means for defining a second grooveadjacent said lip means and spring means, disposed in said secondgroove, for biasing said lip means against said shaft.
 6. The sealaccording to claim 5 wherein the metal retainer means comprises radiallyinwardly extending step means for facilitating separation of the metalretainer means from said housing bore.
 7. The Seal according to claim 6wherein the plastic ring includes means defining flats on an outsidesurface thereof, for restricting rotary motion of the plastic ring.
 8. Arotary cartridge seal stack assembly comprising:a plurality of rotarycartridge seals disposed in and abutting relationship between a housingbore and a shaft, each rotary cartridge real comprising: a cold flowableplastic ring having body means for sealably engaging a housing bore andlip means for sealably engaging a shaft rotating within said housingbore; separable metal retainer means for fixing said plastic ring withinsaid housing bore and around said shaft, said separable metal retainermeans having a surface of revolution with a rear portion having adiameter suitable for press fitting into said housing bore and a frontportion of lesser diameter ending in a ring; and means defining aninternal groove in said body means for engaging the ring therein inorder to latch the plastic ring and metal retainer means together withresidual stress in an axial direction within the plastic ring due to thegroove and ring dimensions and shape, said internal groove having adiameter greater than the ring and wherein a width of said internalgroove is smaller than a width of the ring in order to maintain axialstress in the plastic ring.
 9. The seal according to claim 8 whereinsaid internal groove is generally rectangular with a dovetail sidewallfacing a rear side of said ring.
 10. The seal according to claim 8wherein the metal retainer means forward portion includes means defininga thin cross section in the forward portion, for providing a radialforce on the plastic ring body means in order to cause radial stresstherein.
 11. The seal according to claim 10 wherein the forward portionof the metal retainer means includes means, defining longitudinalgrooves on a inside surface thereof, for providing enhanced radialstress in the plastic ring body means.
 12. The seal according to claim11 wherein the plastic ring includes means, defining flats on an outsidesurface thereof, for restricting rotary motion of the plastic ring. 13.The seal according to claim 10 wherein said plastic ring is U-shaped andfurther comprising spring means, disposed between said lip means andsaid body means for biasing said lip means against said shaft, saidspring means being disposed in a position bearing against the metalretainer means from portion.
 14. The seal according to claim 8 whereinsaid plastic ring is U-shaped and further comprising spring means,disposed between said lip means and said body means for biasing said lipmeans against said shaft, said spring means being disposed in a positionbearing against the metal retainer means front portion.
 15. A rotarycartridge seal stack assembly compressing:a plurality of rotarycartridge seals disposed in an abutting relationship between a housingbore and a shaft, each rotary cartridge real comprising: a cold flowableplastic ring having body means for sealably engaging a housing bore andlip means for sealably engaging a shaft rotating within said housingbore; spring means, disposed between the body means and the lip means,for biasing said lip means against the shaft; separable metal retainermeans for fixing said plastic ring and spring within said housing boreand around said shaft, said separable metal retainer means having asurface of revolution with a rear portion having a radius suitable forpress fitting into said housing bore and a front portion of lesserradius ending in a ring, said rear portion and ring being connected by athin spring portion; and means defining an internal groove in said bodymeans for engaging the ring therein in order to latch the plastic ringand metal retainer means together with residual stress in a radialdirection within the plastic ring due to biasing action by the retainermeans spring portion.
 16. The seal according to claim 15 wherein theretainer means further includes step means, inwardly depending from saidrear portion, for both holding the spring means between the body meansand lip means, and for facilitating removal of the seal from engagementwith the housing bore and shaft.
 17. The seal according to claim 15wherein the retainer means further includes step means, inwardlydepending from said rear portion and having a selected thickness, forcontrolling the force needed to press fit the retainer means into thehousing bore.
 18. The seal according to claim 15 wherein said rearportion comprises a thin flange spring for engaging the housing bore.19. The seal according to claim 18 wherein said body means furthercomprises inwardly depending on flange means for both holding the springmeans between the body means and lip means, and for facilitating removalof the seal from engagement with the housing bore and shaft.
 20. Theseal according to claim 15 wherein the retainer means rear portioncomprises a plurality of load rings for engagement with said housingbore.
 21. The seal according to claim 15 wherein the retainer means rearportion is undercut for controlling engagement force between the bodyportion and the housing bore.
 22. The seal according to claim 21 whereinsaid undercut is radial.
 23. The seal according to claim 21 wherein saidundercut is axial.
 24. A rotary cartridge seal stack assemblycomprising:a plurality of rotary cartridge seals disposed in an abuttingrelationship between a housing bore and a shaft, each rotary cartridgereal comprising: a cold flowable plastic ring having body means forsealably engaging a housing bore and lip means for sealably engaging ashaft rotating within said housing bore; spring means, disposed betweenthe body means and the lip means, for biasing said lip means against theshaft; separable metal retainer means for fixing said plastic ringwithin said housing bore and around said shaft, said separable metalretainer means having a surface of revolution with a rear portion havinga radius suitable for press fitting into said housing bore and a frontportion of lesser radius ending in a ring; means defining an internalgroove in said body means for engaging the ring therein in order tolatch the plastic ring and metal retainer means together; and springportion means, connecting the retainer rear portion and ring, forcontrolling residual stress in a radial direction within the plasticring and preventing shrinkage of the plastic ring toward the shaft. 25.The seal according to claim 24 wherein the retainer means furtherincludes stop means, inwardly depending from said rear portion, for bothholding the spring means between the body means and lip means, and forfacilitation removal of the seal from engagement with the housing boreand shaft.
 26. The seal according to claim 24 wherein said rear portioncomprises a thin flange spring for engaging the housing bore.
 27. Theseal according to claim 26 wherein said body means further comprisesinwardly depending flange means for both holding the spring meansbetween the body means and lip means, and for facilitating removal ofthe seal from engagement with the housing bore and shaft.
 28. The sealaccording to claim 24 wherein the retainer means further includes stepmeans, inwardly depending from said rear portion and having a selectedthickness, for controlling the force needed to press fit the retainermeans into the housing bore.
 29. The seal according to claim 24 whereinthe retainer means rear portion comprises a plurality of load rings forengagement with said housing bore.
 30. The seal according to claim 24wherein the retainer means rear portion is undercut for controllingengagement force between the body portion and the housing bore.
 31. Theseal according to claim 30 wherein said undercut is radial.
 32. The sealaccording to claim 30 wherein said undercut is axial.